A Numerical Model for Multiphase Flow and Transport Assessment of Migration of Petroleum Contaminants in the Subsurface

Huyakorn, P. S.; Panday, S.; Wu, Y. S.; ,

A Numerical Model for Multiphase Flow and Transport Assessment of Migration of Petroleum Contaminants in the Subsurface

by P. S. Huyakorn,
S. Panday,
Y. S. Wu,

Document Type: Proceeding Paper

Part of: Engineering Hydrology

Abstract:

Modeling assessment of the subsurface migration and fate of petroleum hydrocarbons plays a critical role in addressing the environmental impacts of their numerous underground releases nationwide. Practical application of these models, requires incorporating all significant physical processes in the governing equations, which have to be solved using robust numerical schemes that alleviate mass balance problems, convergence difficulties and excessive computational burden arising from the highly nonlinear coupled equations. A comprehensive three-dimensional numerical model for practical assessment of hydrocarbon contamination is examined here. The model is based on a three-phase formulation with equilibrium partitioning of contaminant among the phases to allow for volatilization and dissolution of the hydrocarbon, transport of which occurs by advection and dispersion in all phases. Adsorption, precipitation and first-order degradation processes are also considered. The flow formulation collapses to its simpler forms when air-phase dynamics are neglected, capillary effects are neglected, or two-phase air-liquid, liquid-liquid systems with one or two active phases are considered. Robust and efficient numerical techniques are employed to enable practical simulations of site-specific field problems on PC's and minicomputers. Simulation examples depict the migration of light and dense hydrocarbons and their soluble components in the subsurface. The significance of various modeling assumptions are examined in view of modeling and data requirements and reliability of simulation results.

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